I released several "Type 0" free and open source software in the past. And making people pay for using them, would be the worst I could have done. The software I release as FOSS, is basically stuff I would have coded anyway. But by releasing it for free and as open source, i got following in return:

* Feedback with ideas I wouldn't have come up with myself, that helped me to improve my software.

* Free testers, that reported bugs, I wouldn't have found myself.

* Free contributors, that sent me patches for features and bug fixes I would had to spend my own time on otherwise.

* A nice portfolio, future employers can look at, making it more likely that they hire me.

However making people pay for using my software, will reduce the number of people using my software, and so the number of people who will give feedback, report bugs, and contribute patches. Also people paying for something are less likely to contribute. They are more likely to expect that it is my job to make sure that the software behaves like they expect, since they are paying me for it. But 10-15$ per user, is much less money as I would save by releasing it for free, increasing the number of users/testers and their motivation to contribute.